They spray water (or alcohol, or even nitrous, depening on how deep your wallet is) on the core to chill the intercooler more.
The IC will be pretty hot, as it's an air radiator, and it loses it heat into the passing air.
spraying it with water or something fancy cools it even more but it's unlikely you'll feel a difference.
If you can trust yourself not to push it too far, you can get a boost gauge and a bleed valve.
It's a full mechanical turbo, so bleeding off the vacuum stops the turbo from opening the wastegate as early, and will up the boost.
Newer stuff has an ECU controlled vacuum solenoid that means the ECU decides when to allow the vacuum through to open the wastegate (or move vanes on the clever stuff)
The problem is that it's very easy to keep fiddling with a bleed valve, and keep turning it up until something breaks, so don't go crazy.
Bleed valves are rarely seen these days as the control of turbos has moved on, but the reason most Renault 5 GT turbo owners can swap a headgasket in 20 mins is from fiddling, overboosting and blowing the engine!
cool. mibi just leave the nitrous, not got cash to burn that quickly anyway lol. going to get it chipped, contacted the guy from end tunning, going to strip my ecu down today to see if its the 1 or 2 chip ecu.